Gamma-ray Burst 210901A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:05:56 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     1071488,   Seg_Num: 0
GRB_RA:          295.292d {+19h 41m 10s} (J2000),
                 296.037d {+19h 44m 09s} (current),
                 293.554d {+19h 34m 13s} (1950)
GRB_DEC:         -76.932d {-76d 55' 55"} (J2000),
                 -76.880d {-76d 52' 46"} (current),
                 -77.047d {-77d 02' 49"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1136 [image_cnts]
TRIGGER_DUR:     64.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        19458 TJD;   244 DOY;   21/09/01
GRB_TIME:        54276.34 SOD {15:04:36.34} UT
GRB_PHI:         -44.64 [deg]
GRB_THETA:        47.22 [deg]
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    10.87 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  +0  +0  +0 +29  +0 
SUN_POSTN:       160.97d {+10h 43m 53s}   +8.04d {+08d 02' 39"}
SUN_DIST:        107.18 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.30d {+06h 21m 13s}  +25.76d {+25d 45' 22"}
MOON_DIST:       127.91 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      317.58,-29.18 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      279.54,-54.33 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 204.94,-17.55 [deg].

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:07:45 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     1071488,   Seg_Num: 0
GRB_RA:          295.2878d {+19h 41m 09.07s} (J2000),
                 296.0327d {+19h 44m 07.84s} (current),
                 293.5507d {+19h 34m 12.17s} (1950)
GRB_DEC:         -76.9261d {-76d 55' 33.9"} (J2000),
                 -76.8739d {-76d 52' 25.8"} (current),
                 -77.0412d {-77d 02' 28.4"} (1950)
GRB_ERROR:       5.2 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.86e-09 [erg/cm2/sec]
GRB_SIGNIF:      8.83 [sigma]
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54427.74 SOD {15:07:07.74} UT,   151.4 [sec] since BAT Trigger Time
TAM[0-3]:        327.64 237.16 261.66 243.64
AMPLIFIER:       2
WAVEFORM:        134
SUN_POSTN:       160.97d {+10h 43m 53s}   +8.04d {+08d 02' 37"}
SUN_DIST:        107.18 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.32d {+06h 21m 17s}  +25.76d {+25d 45' 24"}
MOON_DIST:       127.92 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      317.59,-29.18 [deg] galactic lon,lat of the burst
ECL_COORDS:      279.54,-54.33 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        The XRT position is 0.37 arcmin from the BAT position.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:07:55 UT
NOTICE_TYPE:     Swift-XRT Image
TRIGGER_NUM:     1071488,   Seg_Num: 0
GRB_RA:          295.2878d {+19h 41m 09.0s} (J2000),
                 296.0327d {+19h 44m 07.8s} (current),
                 293.5507d {+19h 34m 12.1s} (1950)
GRB_DEC:         -76.9261d {-76d 55' 33.9"} (J2000),
                 -76.8739d {-76d 52' 25.8"} (current),
                 -77.0412d {-77d 02' 28.4"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       78 [cnts]
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54427.74 SOD {15:07:07.74} UT,   151.4 [sec] since BAT Trigger Time
CENTROID_X:      265.40,  raw= 265  [pixels]
CENTROID_Y:      297.91,  raw= 298  [pixels]
ROLL:            227.71 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -0.42
GRB_POS_XRT_Z:   -98.99
IMAGE_URL:       sw01071488000msxps_rw.img
SUN_POSTN:       160.97d {+10h 43m 53s}   +8.04d {+08d 02' 37"}
SUN_DIST:        107.18 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.32d {+06h 21m 17s}  +25.76d {+25d 45' 24"}
MOON_DIST:       127.92 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      317.59,-29.18 [deg] galactic lon,lat of the burst
ECL_COORDS:      279.54,-54.33 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:08:00 UT
NOTICE_TYPE:     Swift-XRT Processed Image
TRIGGER_NUM:     1071488,   Seg_Num: 0
GRB_RA:          295.2878d {+19h 41m 09.0s} (J2000),
                 296.0327d {+19h 44m 07.8s} (current),
                 293.5507d {+19h 34m 12.1s} (1950)
GRB_DEC:         -76.9261d {-76d 55' 33.9"} (J2000),
                 -76.8739d {-76d 52' 25.8"} (current),
                 -77.0412d {-77d 02' 28.4"} (1950)
GRB_ERROR:       5.0 [arcsec, radius, statistical plus systematic]
GRB_INTEN:       78 [cnts]
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54427.74 SOD {15:07:07.74} UT,   151.4 [sec] since BAT Trigger Time
CENTROID_X:      265.40,  raw= 265  [pixels]
CENTROID_Y:      297.91,  raw= 298  [pixels]
ROLL:            227.71 [deg]
GAIN:            1
MODE:            3, Long Image mode
WAVEFORM:        134
EXPO_TIME:       2.50 [sec]
GRB_POS_XRT_Y:   -0.42
GRB_POS_XRT_Z:   -98.99
IMAGE_URL:       sw01071488000msxps_rw.img
SUN_POSTN:       160.97d {+10h 43m 53s}   +8.04d {+08d 02' 37"}
SUN_DIST:        107.18 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.32d {+06h 21m 17s}  +25.76d {+25d 45' 24"}
MOON_DIST:       127.92 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      317.59,-29.18 [deg] galactic lon,lat of the burst
ECL_COORDS:      279.54,-54.33 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Processed Image.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:08:31 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     1071488,   Seg_Num: 0
GRB_RA:          295.292d {+19h 41m 10s} (J2000),
                 296.037d {+19h 44m 09s} (current),
                 293.554d {+19h 34m 13s} (1950)
GRB_DEC:         -76.932d {-76d 55' 55"} (J2000),
                 -76.880d {-76d 52' 46"} (current),
                 -77.047d {-77d 02' 49"} (1950)
GRB_DATE:        19458 TJD;   244 DOY;   21/09/01
GRB_TIME:        54276.34 SOD {15:04:36.34} UT
TRIGGER_INDEX:   20000
GRB_PHI:         -44.64 [deg]
GRB_THETA:        47.22 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     64.000 [sec] 
SOLN_STATUS:     0x13
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    10.87 [sigma]
LC_URL:          sw01071488000msb.lc
SUN_POSTN:       160.97d {+10h 43m 53s}   +8.04d {+08d 02' 36"}
SUN_DIST:        107.18 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.33d {+06h 21m 19s}  +25.76d {+25d 45' 25"}
MOON_DIST:       127.91 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      317.58,-29.18 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      279.54,-54.33 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is an image trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 204.94,-17.55 [deg].

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:10:17 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.379d {+19h 41m 31s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 26"} (J2000)
POINT_ROLL:      227.709d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54433.94 SOD {15:07:13.94} UT,   157.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.998
N_STARS:         72
X_OFFSET:        672 [pixels]
Y_OFFSET:        416 [pixels]
X_MAX:           1631 [pixels]
Y_MAX:           1375 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw01071488000msufc0157.fits
SUN_POSTN:       160.97d {+10h 43m 54s}   +8.04d {+08d 02' 35"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.34d {+06h 21m 23s}  +25.76d {+25d 45' 27"}
MOON_DIST:       127.93 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:10:31 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.379d {+19h 41m 31s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 26"} (J2000)
POINT_ROLL:      227.709d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54433.94 SOD {15:07:13.94} UT,   157.6 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        1.998
N_STARS:         72
X_OFFSET:        672 [pixels]
Y_OFFSET:        416 [pixels]
X_MAX:           1631 [pixels]
Y_MAX:           1375 [pixels]
DET_THRESH:      12
PHOTO_THRESH:    6
SL_URL:          sw01071488000msufc0157.fits
SUN_POSTN:       160.97d {+10h 43m 54s}   +8.04d {+08d 02' 34"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.35d {+06h 21m 23s}  +25.76d {+25d 45' 27"}
MOON_DIST:       127.93 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:11:40 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.379d {+19h 41m 31s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 26"} (J2000)
ROLL:            227.709d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54433.94 SOD {15:07:13.94} UT,   157.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     652201661
X_OFFSET:        990 [pixels]
Y_OFFSET:        779 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1150
Y_GRB_POS:       939
BINNING_INDEX:   1
IM_URL:          sw01071488000msuni0185.fits
SUN_POSTN:       160.97d {+10h 43m 54s}   +8.04d {+08d 02' 33"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.36d {+06h 21m 26s}  +25.76d {+25d 45' 29"}
MOON_DIST:       127.93 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:11:47 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.379d {+19h 41m 31s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 26"} (J2000)
ROLL:            227.709d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54433.94 SOD {15:07:13.94} UT,   157.6 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     652201661
X_OFFSET:        990 [pixels]
Y_OFFSET:        779 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1150
Y_GRB_POS:       939
BINNING_INDEX:   1
IM_URL:          sw01071488000msuni0185.fits
SUN_POSTN:       160.97d {+10h 43m 54s}   +8.04d {+08d 02' 33"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.36d {+06h 21m 26s}  +25.76d {+25d 45' 29"}
MOON_DIST:       127.93 [deg]
MOON_ILLUM:      29 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:18:15 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.390d {+19h 41m 34s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 25"} (J2000)
POINT_ROLL:      227.697d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54591.96 SOD {15:09:51.96} UT,   315.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.809
N_STARS:         42
X_OFFSET:        670 [pixels]
Y_OFFSET:        459 [pixels]
X_MAX:           1629 [pixels]
Y_MAX:           1418 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw01071488000msufc0315.fits
SUN_POSTN:       160.98d {+10h 43m 55s}   +8.04d {+08d 02' 27"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.42d {+06h 21m 40s}  +25.76d {+25d 45' 36"}
MOON_DIST:       127.94 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:19:22 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.390d {+19h 41m 34s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 25"} (J2000)
ROLL:            227.697d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54591.96 SOD {15:09:51.96} UT,   315.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     652201819
X_OFFSET:        990 [pixels]
Y_OFFSET:        779 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1150
Y_GRB_POS:       939
BINNING_INDEX:   1
IM_URL:          sw01071488000msuni0343.fits
SUN_POSTN:       160.98d {+10h 43m 55s}   +8.04d {+08d 02' 26"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.43d {+06h 21m 43s}  +25.76d {+25d 45' 38"}
MOON_DIST:       127.94 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:18:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.390d {+19h 41m 34s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 25"} (J2000)
POINT_ROLL:      227.697d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54591.96 SOD {15:09:51.96} UT,   315.6 [sec] since BAT Trigger Time
FILTER:          7, U
BKG_MEAN:        0.809
N_STARS:         42
X_OFFSET:        670 [pixels]
Y_OFFSET:        459 [pixels]
X_MAX:           1629 [pixels]
Y_MAX:           1418 [pixels]
DET_THRESH:      8
PHOTO_THRESH:    3
SL_URL:          sw01071488000msufc0315.fits
SUN_POSTN:       160.98d {+10h 43m 55s}   +8.04d {+08d 02' 27"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.42d {+06h 21m 41s}  +25.76d {+25d 45' 37"}
MOON_DIST:       127.94 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:18:38 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     1071488,   Seg_Num: 0
GRB_RA:          295.2774d {+19h 41m 06.57s} (J2000),
                 296.0223d {+19h 44m 05.35s} (current),
                 293.5402d {+19h 34m 09.65s} (1950)
GRB_DEC:         -76.9261d {-76d 55' 33.9"} (J2000),
                 -76.8739d {-76d 52' 25.9"} (current),
                 -77.0412d {-77d 02' 28.2"} (1950)
GRB_ERROR:       1.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54562.00 SOD {15:09:22.00} UT,   285.7 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       160.98d {+10h 43m 55s}   +8.04d {+08d 02' 27"}
SUN_DIST:        107.18 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.42d {+06h 21m 41s}  +25.76d {+25d 45' 37"}
MOON_DIST:       127.93 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      317.59,-29.17 [deg] galactic lon,lat of the burst
ECL_COORDS:      279.53,-54.32 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        This position was enhanced using UVOT field astrometry.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 0.11% < P(seren) < 0.58%.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:19:37 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.390d {+19h 41m 34s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 25"} (J2000)
ROLL:            227.697d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  54591.96 SOD {15:09:51.96} UT,   315.6 [sec] since BAT Trigger Time
FILTER:          7, U
EXPOSURE_ID:     652201819
X_OFFSET:        990 [pixels]
Y_OFFSET:        779 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1150
Y_GRB_POS:       939
BINNING_INDEX:   1
IM_URL:          sw01071488000msuni0343.fits
SUN_POSTN:       160.98d {+10h 43m 55s}   +8.04d {+08d 02' 26"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.43d {+06h 21m 43s}  +25.76d {+25d 45' 38"}
MOON_DIST:       127.94 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the XRT Position Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #30746
S. Laha (GSFC/UMBC/CRESST), E. Ambrosi (INAF-IASFPA), V. D'Elia (SSDC & INAF-OAR), P. A. Evans (U Leicester), C. Gronwall (PSU), J. A. Kennea (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift Observatory Team:
At 15:04:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210901A (trigger=1071488). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 295.292, -76.932 which is
```
   RA(J2000) = 19h 41m 10s
   Dec(J2000) = -76d 55' 55"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 60 sec. As this is an image trigger a more complete description of the lightcurve will require the ground pass data. The peak count rate was ~500 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 15:07:07.7 UT, 151.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 295.2774, -76.9263 which is equivalent to:
```
   RA(J2000)  = 19h 41m 06.57s
   Dec(J2000) = -76d 55' 34.8"
```
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 23 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.02 x 10^21 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 1.86e-09 erg cm^-2 s^-1 (0.2-10 keV).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 157 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.200.
Burst Advocate for this burst is S. Laha (sib.laha AT gmail.com). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:25:11 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.389d {+19h 41m 33s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 23"} (J2000)
POINT_ROLL:      227.699d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  55146.25 SOD {15:19:06.25} UT,   869.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.348
N_STARS:         98
X_OFFSET:        430 [pixels]
Y_OFFSET:        219 [pixels]
X_MAX:           1869 [pixels]
Y_MAX:           1658 [pixels]
DET_THRESH:      19
PHOTO_THRESH:    11
SL_URL:          sw01071488000msufc0869.fits
SUN_POSTN:       160.98d {+10h 43m 56s}   +8.04d {+08d 02' 21"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.48d {+06h 21m 56s}  +25.76d {+25d 45' 44"}
MOON_DIST:       127.95 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:26:38 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.389d {+19h 41m 33s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 23"} (J2000)
ROLL:            227.699d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  55146.25 SOD {15:19:06.25} UT,   869.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     652202373
X_OFFSET:        989 [pixels]
Y_OFFSET:        778 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1149
Y_GRB_POS:       938
BINNING_INDEX:   1
IM_URL:          sw01071488000msuni0897.fits
SUN_POSTN:       160.98d {+10h 43m 56s}   +8.04d {+08d 02' 20"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.50d {+06h 21m 59s}  +25.76d {+25d 45' 46"}
MOON_DIST:       127.95 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:25:29 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.389d {+19h 41m 33s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 23"} (J2000)
POINT_ROLL:      227.699d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  55146.25 SOD {15:19:06.25} UT,   869.9 [sec] since BAT Trigger Time
FILTER:          10, White
BKG_MEAN:        5.348
N_STARS:         98
X_OFFSET:        430 [pixels]
Y_OFFSET:        219 [pixels]
X_MAX:           1869 [pixels]
Y_MAX:           1658 [pixels]
DET_THRESH:      19
PHOTO_THRESH:    11
SL_URL:          sw01071488000msufc0869.fits
SUN_POSTN:       160.98d {+10h 43m 56s}   +8.04d {+08d 02' 21"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.49d {+06h 21m 57s}  +25.76d {+25d 45' 45"}
MOON_DIST:       127.95 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.  
COMMENTS:        All 4 attachments are included.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Wed 01 Sep 21 15:26:45 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     1071488,   Seg_Num: 0
POINT_RA:        295.389d {+19h 41m 33s} (J2000)
POINT_DEC:       -76.907d {-76d 54' 23"} (J2000)
ROLL:            227.699d
IMG_START_DATE:  19458 TJD;   244 DOY;   21/09/01
IMG_START_TIME:  55146.25 SOD {15:19:06.25} UT,   869.9 [sec] since BAT Trigger Time
FILTER:          10, White
EXPOSURE_ID:     652202373
X_OFFSET:        989 [pixels]
Y_OFFSET:        778 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1149
Y_GRB_POS:       938
BINNING_INDEX:   1
IM_URL:          sw01071488000msuni0897.fits
SUN_POSTN:       160.98d {+10h 43m 56s}   +8.04d {+08d 02' 20"}
SUN_DIST:        107.21 [deg]   Sun_angle= -9.0 [hr] (East of Sun)
MOON_POSTN:       95.50d {+06h 21m 59s}  +25.76d {+25d 45' 46"}
MOON_DIST:       127.95 [deg]
MOON_ILLUM:      28 [%]
GAL_COORDS:      317.61,-29.20 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      279.58,-54.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        All 4 attachments are included.

GCN Circular #30747
V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University)
MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 210901A ( S. Laha et al., GCN 30746) errorbox 6860 sec after notice time and 6950 sec after trigger time at 2021-09-01 17:00:26 UT, with upper limit up to 18.6 mag. Observations started at twilight. The observations began at zenith distance = 49 deg. The sun altitude is -8.9 deg.
The galactic latitude b = -30 deg., longitude l = 318 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1706835
We obtain a following upper limits.
```
Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    7040 |         MASTER-SAAO |   C |   180 | 17.4 |        
    7220 |         MASTER-SAAO |   C |   540 | 17.8 |  Coadd 
    7240 |         MASTER-SAAO |   C |   180 | 17.9 |        
    7439 |         MASTER-SAAO |   C |   180 | 18.3 |        
    7639 |         MASTER-SAAO |   C |   180 | 18.6 |        
```
Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
GCN Circular #30748
R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:
We observed Swift GRB 210901A (Laha, et al., GCN 30746) with the LCO 1-m Sinistro instrument at the South African Astronomical Observatory site, on September 1, from 17:14 to 17:36 UT (corresponding to 2.17 to 2.53 hours from the GRB trigger time) with the Bessel R and I filters.
We performed a series of 3x300s exposures in R and I. In the XRT detection region (Laha, et al., GCN 30746) no optical counterpart could be detected down to the following upper limits, calculated using the USNO-B.1 catalog as reference:
R>21.55
I>21.16
These magnitudes are not corrected for galactic extinction.
R.S. is funded by NSF AST grant #1831682
GCN Circular #30749
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
Using 302 s of XRT Photon Counting mode data and 1 UVOT images for GRB 210901A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 295.27805, -76.92664 which is equivalent to:
```
RA (J2000): 19h 41m 6.73s
Dec (J2000): -76d 55' 35.9"
```
with an uncertainty of 2.5 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN Circular #30750
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210901A (trigger #1071488) (Laha et al., GCN Circ. 30746). The BAT ground-calculated position is RA, Dec = 295.224, -76.942 deg which is
```
   RA(J2000)  =  19h 40m 53.8s
   Dec(J2000) = -76d 56' 31.9"
```
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 12%.
The mask-weighted light curve shows a multi-peaked structure. The main pulse structure start at ~T+30 s and ends at ~T+85 s, with the highest peak occurring at ~T+60 s. In addition, there might be some weak emission prior to the main pulses and starts at ~T-50 s. T90 (15-350 keV) is 46.77 +- 7.87 sec (estimated error including systematics).
The time-averaged spectrum from T+29.77 to T+84.70 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.08 +- 0.17. The fluence in the 15-150 keV band is 3.1 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+60.64 sec in the 15-150 keV band is 2.4 +- 0.6 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1071488/BA/
GCN Circular #30751
J.A. Kennea (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU) and S. Laha report on behalf of the Swift-XRT team:
We have analysed 2.5 ks of XRT data for GRB 210901A (Laha et al. GCN Circ. 30746), from 139 s to 79.9 ks after the BAT trigger. The data comprise 126 s in Windowed Timing (WT) mode (the first 7 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 30749).
The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=2.8 (+0.3, -0.4). At T+207 s the decay steepens to an alpha of 5.1 (+/-0.4) before breaking again at T+517 s to a final decay with index alpha=0.60 (+/-0.09).
A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.55 (+0.14, -0.13). The best-fitting absorption column is 2.8 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 1.0 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.0 (+0.4, -0.3) and a best-fitting absorption column of 1.7 (+1.2, -0.6) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     1.7 (+1.2, -0.6) x 10^21 cm^-2
Galactic foreground: 1.0 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.0 (+0.4, -0.3)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01071488.
This circular is an official product of the Swift-XRT team.
GCN Circular #30755
A. Nicuesa Guelbenzu, S. Klose (both TLS Tautenburg), and A. Rau (MPE Garching) report:
We observed the field of GRB 210901A (Swift trigger #1071488; Laha et al., GCN 30746) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m MPG telescope at La Silla Observatory (Chile).
Observations started at 23:43 UT on September 1, about 8.5 hr after the GRB trigger. They were performed at an average seeing of 2.3 arcsec and at an average airmass of 1.5.
Inside the 2.5 arcsec enhanced XRT error circle (Osborne et al., GCN 30749), we do not detect any source. Based on an observation with 23.4 minutes integration time in g'r'i'z' and 20 minutes in JHK, at a midtime of 23:43 UT on September 1, we measure the following preliminary 3-sigma upper limits (AB mags):
```
g' > 23.5,
r' > 23.6,
i' > 22.6,
J  > 20.1,
H  > 19.7, and
K  > 16.3.
```
We note the presence of an object at the north-western border of the XRT error circle at coordinates RA, DEC (J2000) = 19:41:05.98, -76:55:33.0 for which we measure r' = 21.33 +/- 0.05 mag (AB). Due to the relatively bad seeing at present we cannot decide with certainty if this is a galaxy or a star.
Given magnitudes are calibrated against the SkyMapper catalog (Wolf et al., 2018, PASA 35, e010) in g'r'i'z' and 2MASS field stars in JHK (Skrutskie et al., 2006, AJ 131, 1163).
We thank Maren Hempel for excellent support and for performing the observations.
GCN Circular #30767
M. H. Siegel (PSU) and S. L. Laha (GSFC/UMBC/CRESST) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210901A 158 s after the BAT trigger (Laha et al., GCN Circ. 30746). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 30749) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           158          308          147         >20.9
u_FC               316          566          246         >19.6
white              158          974          289         >20.9
v                  646          839           39         >17.8
b                  572          764           39         >18.8
u                  316          740          265         >19.8
w1                 695          715           19         >17.8
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.200 in the direction of the burst (Schlegel et al. 1998).

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Jochen Greiner, last update: 05-Sep-2021 [Disclaimer]